Bryngwyn Colliery Engine House

Bryngwyn Colliery Engine House is a two-storey ruined engine house featuring two windows and a plinth. The roof, north wall, and part of the west wall are no longer present. It is built from coursed rubble sandstone with raised quoins and grey brick facings. The building has round-headed openings with voussoirs, raised keystones, imposts, and stone sills. Some of the openings are badly eroded, and the lower ones may have been enlarged to remove machinery. The south end of the building has one large opening on each storey. A high plinth made of larger stones supports the structure.

Tie rods run through the engine house at first floor level, with two at the south end and one at the north end, each featuring circular tie plates. Inside, the cylinder bed is located on the north side at ground floor level, with a pit in the southern half of the plinth. Wide round-arched openings with large voussoirs provide access through the south wall of the plinth and beneath the cylinder bed to the north. Horizontal rods are believed to have passed through these openings, with those to the south connected to the pump rods and those to the north linked to a balance box. The east and west sides of the plinth have round-headed openings similar to those above, all featuring yellow brick soffits. There are four large sockets in the south wall of the plinth at shoulder height of the round arch and at first floor sill level, along with additional sockets at the north end of the internal east wall at first floor level. Joist holes are present at the first floor.